Papermaking machine



' Dec. 25, 1956 u. G. SDERLUND PAFERMAKING MACHINE Filed Aug. 25, 1954 iINVENTOR.

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United States Patent O 2,775,169 PAPERMAKING MACHINE t Ulf GustavSderlund, Norrkoping, Sweden, assiguor to Aktiebolaget KarlstadsMekaniska Werkstad, Karlstad, Sweden, a company of Sweden This inventionrelates to paper making machines, such as machines of the Fourdriniertype, wherein wet pulp is fed to and spread evenly upon the surface of amoving wire to form a wet web sheet thereon, the web fed through aseries of press rolls which serve to remove water, consolidate the web,and remove the impressions produced in the web by the wire, and the webthereafter dried and calendered. ln machines of this generalorganization, it is customary to guide the web in its travel through oneor more of the press units` either between continuous moving felt stripsor upon a single continuous moving felt strip, the web in either casebeing positively supported on top of a moving felt strip.

ln the present invention the paper web `is removed r picked off theforming wire by a rotating transfer roll,

' preferably with the help of suction, `and thelweb transferred to anupper felt strip. The wet web inherently adheres to the underside of thefelt strip, and the web is thereby carried, without lower support,through one or more of the press units.

In the conventional design of the press units of paper making machines,the lower roll is a suction roll journaled in fixed bearings, whereasthe bearings of the upper roll are movable toward the lower roll, thepressure therebetween being determined by the weight of the upper roll.The purpose of the suction, in machines of conventional design, is toremove water from the web and the felt strip and since the peripheralsurface of the `suction roll is ordinarily perforated, it is deemedpreferably that the suction roll engage the felt rather than the webdirectly. In the present invention there is no lower felt, but only theupper felt. Nevertheless, it is feasible, in the present invention, toutilize a suction press to` withdraw water from the web by inverting theconventional rolls. Thus, in the present inventionthe upper roll is thesuction roll and the bottom roll is a plain roll. ln this way, thesuction roll engages the felt, rather than the web, and the suctionroll, in addition, helps to tix` the web to the lower surface of thefelt in a cohesive relationship.

In the preferred form of Vthe invention, the top suction roll isjournaled in xed bearings and provision is made for raising the plainbottom roll into engagement with the top suction roll with the desiredpressure. Thus, a controllable pressure may be realized between theupper and lower press rolls so that it is not necessary to rely merelyon the weight of the uppertroll. Furthermore, the fact that the uppersuction roll need not be adjustable toward and away from the lower plainroll is an important advantage inasmuch as the connections to thesuction box of the suction roll need not be movable.

The elimination of 'the lower felt strip, of course, affordssimplification in the construction of the machine, and the newarrangement has the further advantage that the web is at all timesaccessible, unobstructed by the lower felt, from the pit beneath thepress. Therefore, in case of a rupture or break of the web, the web maybe brought straight down into the pit instead of having to` be fedthrough the press and beyond the point of separa- "ice tion of the felt.the cohesion between the web and the undersurface of the feltreestablished. In addition, as the lower plain roll of the first pressunit will bear directly against the side of the paper web engaged by thewire, instead of acting through the lower felt, the wire marks thereinwill be effectively smoothed out in the first press unit.

ln the preferred design of the machine, the upper pickup felt travelsessentially in a straight path between the transfer or pick-off roll andthe top roll of the first press unit. ln this way, the paper web,adhering to the under side of the pick-up felt, is not subjected to anychanges of direction which might endanger the cohesion and cause the webto drop off the felt. Thus, the felt may be primarily chosen with regardto its high water absorption qualities, rather than with a view to theadhesiveness of the felt. Of course, the straight path of the web alsofacilitates the repair of the web after rupture and makes it easier toinspect and maintain the machine.

The invention will be more fully described hereinafter with reference tothe accompanying drawing which diagrammatically shows a part of a papermaking machine embodying the present invention. g

Referring to the drawing, the pulp is applied evenly to the `wire l@ ofthe paper making machine forming a web lll which is picked on the wirelil by a rotating transfer roll l2. The web 1l, adhering to the lowersurface of an endless moving felt 13, is carried thereby through a pressunit, generally designated by the reference character A. From the pressunit it is transferred to the top surface ofanother endless continuouslymoving felt 14 which carries the web through another press unit,generally designated by the reference character B. The web is thenconveyed to the drying portion ofthe machine which forms no part of thisinvention.

The web forming wire 10 of the paper making machine travels in a closedcircuit, only part of which is shown in the drawing. in the portionshown, the web is trained over a couch roll l5, preferably a suctiontype roll, and then travels in a downwardly sloping direction to a wiredrive roll 17, passing around part of the circumference of the roll 17to change the direction of travel of the wire. A pressure roll 1S bearsagainst the couch roll 15 and is so journaled that it can be raised inorder to facilitate the change of the wire.

The driven transfer roll 12 bears against the unsupported downwardlyinclined stretch of the wire between the couch roll l5' and the wiredrive roll 17, and the function of the transfer roll 12 is to remove theweb 11 from the wire 10. The transfer roll is journaled in the upperends of arms 19 which are pivotally mounted about pins 2t? to a basestructure 21 anchored to the floor D. The pivotal arms permit thetransfer roll to be translated toward and away from the inclined stretchof the wire, and thus, by adjusting the arms in the desired pivotedposition, the pressure of the transfer roll against the wire and the arcof the circumference of the roll engaged by the web may be regulated asdesired. The transfer roll 12 is preferably in the form `of a perforatedsuction roll` and has a suction zone 22 which is connected by means of`a flexible tube Z3 to a vacuum pump (not shown).

The felt 13 which carries the paper web 11 from the wire 10 to the pressunit A travels inessentially a straight line between the transfer roll12 and the top roll 24 of the press unit A. As explained above,I it isdeemed desirable in order to insure the adherence of the web to theunderside of the felt 13 that the path of travel of the felt beessentially in a straight line and in approximately the horizontaldirection, although in the embodiment illustrated in the drawing thepath of travel of the felt between the transfer roll 12 and the upperroll 24 The web may be readily repaired and of the' prs's unit is in aslightly, but i'nsignicantly, inclined direction'.

The upper roll 24 of the press unit A, in the preferred embodiment, is aperforated suction roll having a suction zone 25 communicating with avacuum pump (not shown) by means of a xed conduit 26. An upper hood 27communicating with the conduit 26 surrounds the greater part of thesuction roll 24 and serves to collect the water thrown out therefrom.

The bottom roll 2S of the press unit A is an idling stone roll journaledbetween arms 30 (only one of which is shown) pivotally mounted to pins31 (only one being shown) of a mounting bracket 32, and the pivotaladjustment of the arms 30 moves the roll 28 towards and away from theperiphery of the upper roll 24. The pivotal action of the arms 30 iscontrolled by a pneumtaic piston 34, 'and the bottom roll 28 can beraised from a lowered position and brought to bear against the top roll24 at a desired pressure by adjusting the pneumatic pressure upon thepiston 34.

r A doctor blade 35 is suitably mounted atthe left side (as viewed inthe drawing) of the roll 23, above a pit 36 formed in the surface of thefloor D beneath the press unit A, and the blade is adapted to bearagainst the periphery of the lower roll 28. In the event of a rupture orbreak of the web between the presses, as well as when initially drawingthe web through the machine, the web is scraped off the surface of theroll 28 by the doctor blade 35, the web running vertically down into thepit 36.

The felt 13, as mentioned above, forms a closed loop engaging thetransfer roll 12 and the top suction roll 24 of the rst press unit. Thefelt is guided in its circuit by a plurality of rolls and runs fromabove to the roll 12,

engaging the periphery thereof throughout a center angle exceeding 90and leaving the transfer roll 12 approximately in the horizontaldirection. Without bearing against any guide roll or similar means, thefelt then runs directly to the first press unit A, its path beingessentially straight between the rolls 12 and 24. Due to the fact thatthe top roll 24 is displaced somewhat at an angle in relation to thelower roll, the felt 13 will engage the lower periphery of the top roll24 somewhat in advance of the bite between the rolls 24 and 28. Afterpassing between the press rolls 24 and 28, the felt runs in an inclined,upward direction, substantially tangential to the bite between the rolls24 and 28, to a guide roll and then travels upwardly over a series ofrolls to complete circuit. Preferably the change of direction of thefelt in passing around the periphery of the suction roll 24 is in theorder of 20 to 30.

The press unit B is of a more conventional design and comprises an upperroll 40' and a suction bottom roll 41 having a suction zone 42. Thepaper web travels from the press unit A over the guide roll 43 to thetop surface of the endless moving felt 14. The felt 14 guides the webthrough the bite between the press rolls 40, 41, the upper roll 40 ofthe press unit B engaging the upper surface of the web. A doctor bladeis adapted to engage the surface of the upper roll 40. After passingthrough the press unit B, the web 11 travels towards the drying sectionof the machine.

In operation, the paper web 11, as mentioned before, is formed on themoving wire 10 and during the downwardly inclined stretch of the wirebetween the suction roll 15 and the drive roll 17, the web is engaged bythe surface of the 'pick-'up felt 13 which, with the help of the 'vacuumof the suction zone 22 of the transfer roll 12, causes the web to adhereto the surface of the felt, whereby the web is transferred from the wire10 to the surface of the flt. Thereafter, the' web fllOWS' the path Ofthe felt around the transfer roll 12 in a straight path toward the pressunit A, the web being held against the felt by cohesion forces ofsuicient magnitude to outweight the effect of gravity on the web. Theweb 11 passes through the bite between the press rolls 24 and 28 of thepress unit A, and, as explained above, the disposition of the rolls ofthe press unit A is such that the web is caused to engage a portion ofthe suction surface of the press roll Thus, although the web, infollowing curved paths around portions of the peripheries of thetransfer roll 12 and the suction roll 24, is influenced by centrifugalforces, the web is, nevertheless, held at these two points by suction asWell as by the cohesive effect of the surface of the felt 13.

The invention has been shown and described in a single preferred formand by way of example only, and it is understood that many variationsand modifications may be made therein without departing from the spiritof the invention. For example, the transfer roll 12 may be applied tothe wire at a point opposite the couch roll 15, that is approximatelywhere the roll 18 is positioned, said roll being removed. Also, ofcourse, the suction boxes may take various forms other than that shown,or may be divided in such a manner that the suction zone of a highervacuum is active at the bite between the rollers and another Zoneadjacent thereto of lower vacuum serves to hold the web against the feltor to prevent water in the perforation holes in the suction roll frombeing thrown out onto the felt. It is understood, therefore, that theinvention is not to be limited to any specified form or embodiment,except insofar as such limitations are eX- pressly set forth in theclaims.

i claim:

l. ln a paper making machine having a wire with au outer surface onwhich a paper web is formed; the combination of a first suction rolladjacent to the outer surface of said wire, a second suction roll spacedfrom said first roll and said wire and substantially parallel with saidrst roll, an endless felt passing around and below said suction rollsand being interposed between and having an inner surface in directengagement with the iirst and second suction rolls and an outer surfaceadjacent to said wire to pick-up said web and carry it away from saidwire, a plain press roll directly beneath said second suction roll andhaving a surface engaging the outer surface of said felt and any webthereon and squeezing them against said second suction roll, the outersurface of said felt being substantially completely exposed between saidwire and said press roll and a scraper engaging the surface of saidpress roll for disengaging a broken web thereon and discharging itdownwardly by gravity.

2. A combination as set forth in claim 1, wherein the first suction rollis adjustable towards and away from the inclined portion of the formingwire.

3. A combination as set forth in claim l, wherein the press roll isadjustable towards and away from the second suction roll and includingmeans to control the pressure of the press roll against the secondsuction roll.

References Cited in the le of this patent UNITED STATES PATENTS2,415,351 Hornbostel et al. Feb. 4, 1947 2,672,078 Hornbostel Mar. 16,1954 2,694,348 Beachler Nov. 16, 1954

